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Background Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging. Methodology/Findings Here we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999-2000 (n = 412) and 2000-2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range,...
Ecologists and conservation biologists alike aim to understand factors determining the abundance and distribution of free-living organisms and to pinpoint why free-ranging animal populations decline. My broad goals were to test ecological hypotheses related to timing of breeding and offspring survival in lesser scaup ( Aythya affinis, hereafter scaup), a boreal-breeding diving duck species and to examine breeding-season explanations for why scaup populations remain below conservation goals. I demonstrated that timing of breeding and clutch size in scaup were remarkably consistent across a broad environmental gradient. Clutch initiation date was unaffected by growing season length (GSL) or latitude and was only marginally...
Background Elucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging. Methodology/Findings Here we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999-2000 (n = 412) and 2000-2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range,...
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We studied nutrient reserve dynamics of female Lesser Scaup (Aythya affinis) to identify sources of intraspecific variation in strategies of nutrient acquisition for meeting the high nutritional and energetic costs of egg formation. We collected data from interior Alaska and combined these with data for Lesser Scaup from midcontinent breeding areas, allowing a range wide analysis for the species. We found little evidence that nutrient reserve use differed between Alaskan and midcontinent Lesser Scaup, except that subarctic birds used a small amount of protein reserves when forming eggs, whereas midcontinent birds did not. Mineral reserves contributed relatively little to the clutch, but endogenous lipid accounted...
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In many waterfowl species, body condition of breeding females can contribute to reproductive success by influencing factors such as egg size, clutch size and ability to incubate eggs. In turn, changes in female condition at the population level could affect population growth rates. Large-scale declines in populations of Lesser Scaup (Aythya affinis) raised concerns that poor female body condition was contributing to declines by reducing reproductive output. However, little was known about changes in body condition over time and about the contribution that stored body reserves make to egg production, especially in boreal forest regions where most scaup breed. My objectives were: 1) examine temporal changes in body...
We examined long-term databases concerning population status of scaup (lesser [Aythya affinis] and greater scaup [A. marila] combined) and harvest statistics of lesser scaup to identify factors potentially limiting population growth. Specifically, we explored evidence for and against the general hypotheses that scaup populations have declined in association with declining recruitment and/or female survival. We examined geographic heterogeneity in scaup demographic patterns that could yield evidence about potential limiting factors. Several biases exist in survey methodology used to estimate scaup populations and harvest statistics; however, none of these biases likely accounted for our major findings that (1) the...
Categories: Publication; Types: Citation; Tags: B5-Lesser Scaup
Habitat management for ducks has significant implications for the conservation of other species. We hypothesized that, because of their flagship and umbrella characteristics, upland-nesting ducks might be effective surrogate species for songbird and shorebird conservation in the dry mixed-grass prairie. We tested this by comparing effects of habitat management (cattle grazing deferments and field size), distance to other habitat (water, cropland/forage, roads), and vegetation, on the richness and density of ducks, songbirds, and shorebirds in southern Alberta, Canada. There were no consistently similar responses to these habitat characteristics among ducks, songbirds and shorebirds. Despite their conceptual appeal,...
One of the proposed explanations for the recent continental decline in Lesser Scaup (Aythya affinis) populations is that females experience lower survival or reproduction resulting from exposure to contaminants in their diet of exotic bivalves during migration and over winter. In 1999, we collected eggs and females from five sites in the boreal forest of Canada and Alaska and four sites in Canadian parkland. We analyzed eggs from 60 clutches and ten nesting females for toxic metals, selenium, 19 pesticides and other organochlorines, and 43 polychlorinated biphenyl (PCB) congeners. The highest organochlorine concentration we measured was 1.5 ?g g?1 ww of DDE in eggs. The highest mercury concentration was 1.8 ?g g?1...
Categories: Publication; Types: Citation; Tags: B5-Lesser Scaup, M1-Birds


map background search result map search result map Intraspecific variation in nutrient reserve use during clutch formation by lesser scaup Body condition and reproductive strategies of female lesser scaup in the boreal forest of Alaska Intraspecific variation in nutrient reserve use during clutch formation by lesser scaup Body condition and reproductive strategies of female lesser scaup in the boreal forest of Alaska